Product not delivered, how to contact Netatmo

A month and a half ago I ordered a smart weather station with rain and wind meter. According to the tracking e-mails the product was shipped and shortly before delivery returned to sender. I've tried to reach somebody from Netatmo, but do not get any response. How can I contact Netatmo to resolve why the products are not delivered, whilst the money for the products is deducted from my account.